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Nonruminants contrast with ruminants in that they do not return their food to their mouth to ferment it. Rather than fermenting in
their foregut, they ferment their food in their hindgut, the caecum (Wolin 1981). As Figure 6 below shows us, the stomach compositions
of nonruminants still varies greatly. Depending on what adapts best to the relative size of an organism the stomach takes on a certain
composition (Demment 1985). Normally this means that the larger the organism gets the larger a fermenting chamber it has, with two
notable exceptions (Demment 1985). The largest ruminant is the hippotamus, and based on our conclusions about the ratio between
herbivores and fermenting capacity they should be the largest herbivores in existence (Demment 1985). However, the elephant is much
larger than the hippopotamus but does not ruminate. The other exception is the human being, which, while being a relatively large
omnivore, has lost its ability to ferment cellulose whatsoever (Hume 1989). The nonruminants use their gastric chambers (shown in red
below) to digest food in a significant amount compared to what they take through themselves. The ruminants on the other hand, will
only use the gastric stomach sections to store food temporarily before moving it elsewhere to be fermented so that they can get the full
possible nutritional value from it (Stevens 2008). Species that don't have the luxury of large size or a long time to digest their food before
they need the energy or to engage in a different activity greatly benefit from not having to chew cud for up to eight hours a
day like cows do (Campbell 1975).
This image used in compliance with the Wikimedia Commons free license.
Figure 6: A color-coded diagram comparing the different sizes and configurations of various nonruminants to ruminants. The yellow represents the esophagus. The green represents the rumen and/or the reticulum. The purple areas represent cardiac glands. The light blue is the site of the pyloric glandsand the dark blue is the beginning of the small intestines. (Adapted from freely licensed text at http://en.wikipedia.org/wiki/File:Mammalian_Stomachs_remake.png)
Please email Brian McRae at Davidson College with any questions.
This website was created as a part of a class project in the Animal Physiology Class at Davidson College.